1. Field of the Invention
The present invention relates in general to digital radio communications and, in particular, to a method and apparatus for error detection in a stream of digital data.
2. Background Art
The transmission of digital data over a radio frequency communication link is very often implemented by transferring the digital data as discrete packets or frames of information from a transmitter to a receiver, as opposed to transferring the data as a continuous homogenous stream of data. In some digital communication systems multiple types, or configurations, of data packets each having different characteristics, such as length and data type, are employed. An example of such transmission of digital data over a radio frequency link may be found in the environment of a cordless telephone. In a digital cordless telephone system multiple types of data are transmitted including both voice data corresponding to the user's voice and command data corresponding to user activated keys and background operation of the phone.
In some digital cordless telephone systems, each packet is formed from the combination of command and audio data the integrity of which is enhanced by implementation of one of various error detection schemes. In these prior art systems having error detection/correction, the error correction data is usually calculated for a data packet as a whole and the resulting error detection/correction data is appended to a particular location in the packet. In practice, many of these error detection schemes require significant processing overhead, which can introduce delay in the transmission of the data over the radio link by requiring completion of processing before transmission can occur. Further, the segregation of synchronization, voice, command and error-detection/correction data in each frame creates an inherent delay in audio data transmission and processing caused by this arrangement of the packets. The segregation tends to require extensive buffering of the separate fields to facilitate bundling of the fields into a frame and, later to facilitate unbundling of those same frames into separate fields.
Inherent delay in digital communication is typically undesirable. Studies have shown that delay in digital audio path decreases the Mean Opinion Score (MOS) for the transmission system, wherein MOS is a commonly used assessment of the quality of the communication link as it relates to speech. This degradation in the observed quality of the communication system has been attributed to various cases, which often results from delay in the audio data path. While introduction of error detection/correction data adds delay, error detection is nevertheless critical to proper functioning of a communication system. Accordingly, it is an object of the present invention to provide an error detection scheme that minimizes delay in the audio path.
It is a further object of the present invention to provide an error detection method and apparatus that minimizes computational overhead, yet provides detection of errors throughout each frame.
These and other objects of the present invention will become obvious to those of ordinary skill in the art based upon the attached specification, drawings and claims.